Random is barely random at all?

Question

I did this to test the randomness of randint:

>>> from random import randint
>>>
>>> uniques = []
>>> for i in range(4500         


        

Answer 1

You have defined a random space of 4501 values (500-5000), and you are iterating 4500 times. You are basically guaranteed to get a collision in the test you wrote.

To think about it another way:

• When the result array is empty P(dupe) = 0
• 1 value in Array P(dupe) = 1/4500
• 2 values in Array P(dupe) = 2/4500
• etc.

So by the time you get to 45/4500, that insert has a 1% chance of being a duplicate, and that probability keeps increasing with each subsequent insert.

To create a test that truly tests the abilities of the random function, increase the universe of possible random values (eg: 500-500000) You may, or may not get a dupe. But you'll get far more iterations on average.